Code 33 - Mass Airflow (MAF) Sensor Signal High: Notes

The Mass Airflow (MAF) sensor measures the flow of air entering the engine. The sensor produces a frequency output between 32-150 hertz). A large quantity (high frequency) indicates acceleration, and a small quantity (low frequency) indicates deceleration or idle. This information is used by the ECM for fuel control and is converted by "Scan" tester to read airflow in grams per second). A normal reading is about 4-7 grams per second at idle, increasing with RPM. The MAF sensor on is powered by a 15-amp fuse located underhood in the right relay center. MAF sensor should have power supplied to it any time the ignition is on.

1. Code 33 will set if the following conditions occur:
   • Ignition on and airflow exceeds 20 grams per second.
   • Engine is running less than 1300 RPM.
   • TPS is 8 percent or less.
   • All the above are met for 2 seconds.